How to Calculate Your Carbon Footprint

Turn your greenhouse gas emissions into hard numbers

If you’re not already mandated to do so, chances are that day isn’t too far into the future, especially as state governments begin to impose restrictions and shareholders expect deeper management considerations of environmental risk.

Companies such as Chevrolet, Intel, Nike, Coca-Cola, and Microsoft are all working to reduce their greenhouse gas emissions. Make calculating your carbon footprint easy by following these three steps.

Much like building certification programs, there are multiple standards for greenhouse gas (GHG) reporting – it’s up to you to determine which one to use.

You might consider the Greenhouse Gas Protocol from World Resources Institute (WRI) and the World Business Council for Sustainable Development (WBCSD), which accommodates complex or multinational organizations.

There are also state versions that include mandatory reporting, such as those required for large emitters by Oregon’s Department of Environmental Quality or California’s Air Resources Board. These protocols offer standardization and technical guidance to facility managers.

If you want to go a simpler route, start by creating a ballpark assessment of your emissions.

The bulk of a building’s footprint is energy use, including electricity, natural gas, and other sources tied to fossil fuel.Review your utility bills and conduct some basic calculations to reveal a large portion of these impacts.

For example, if a building consumes 500 therms of natural gas, multiply by a factor of 11.7 to get the pounds of carbon dioxide emissions: 500 x 11.7 = 5,580 pounds of CO2 from natural gas use.

The same is true for electricity use, where the number of kilowatt-hours consumed over a period is multiplied by the current emissions intensity of your specific grid region (available online through the EPA).